1/4 c salted butter
1 vanilla bean, split lengthwise
All-purpose flour (for dusting)
1 pound baking apples, scrubbed, sliced 1/8″ thick
3 TBSP dark muscovado or dark brown sugar
1 TBSP granulated sugar
1 TBSP sugar
1/2 tsp salt
1 c flour
6 TBSP chilled unsalted butter, cut into pieces
1 egg, beaten to blend
Pulse sugar, salt, and 1 c flour in a food processor. Add butter and pulse until mixture resembles coarse meal with a few pea-size pieces remaining. Drizzle egg over butter mixture and pulse a couple times until dough just comes together.
Turn out dough onto a lightly floured surface and knead until smooth (a few dry spots are okay). Form dough into a disk. Wrap in plastic and chill until firm, at least 2 hours.
For the galette:
Place a rack in middle of oven and preheat to 375°.
Place butter in a small saucepan and scrape in vanilla seeds; add pod. Cook over medium heat, stirring often, until butter foams, then browns (be careful not to burn), 5-8 minutes. Remove pan from heat and remove pod.
Roll out dough on a lightly floured surface into a rough 14×10″ rectangle about 1/8″ thick.
Transfer to a parchment-lined baking sheet. Arrange apples on top, overlapping and leaving a 1 1/2″ border.
Brush apples with brown butter and sprinkle with muscovado sugar. Lift edges of dough over apples, tucking and overlapping as needed to keep rectangular shape.
Beat egg with 1 tsp water in a small bowl and brush crust with egg wash. Sprinkle with granulated sugar and bake, rotating once, until apples are soft and juicy and crust is golden brown, 40-50 minutes. Let cool slightly on baking sheet before slicing.
Serve with whipped cream.
Serves 6 – 8.